Third Parties

Third Parties describes any but the two major parties in the U.S. elections. There is no single Third Party. Instead the term applies to any party that is not Republican or Democrat.
The reason for this is that structure of the U.S. eelctoral system makes a two-party system or two-party dominant system almost inevitable. Note however that the Electoral College permits a third party to spoil the electoral chances of a major party in a deliberate coordination failure, something that has happened repeatedly in U.S. history.

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Third Parties Really Are Doomed, Unless...

In the United States, third parties are doomed from the start. One can quibble about the Republicans replacing the Whigs, but actually that was the exception that proved the rule. The Whigs disappeared as most of their elected officials and voters became Republicans. Replacing an existing party is not the same as creating a viable third party.

The reason for the near futility of third party politics in the United States rests with the structural reality of the First-Past-the Post (FPP) or Single Member District/Plurality (SMD/P)electoral system. Used in Britain and former British colonies, this electoral system systematically disadvantages all but the two largest electoral parties. The result is a two party system or two party dominant system. Third parties either wither or barely hang on because voters respond rationally to the electoral system with strategic voting--choosing the lesser-of-two-evils within the two party system. Third parties are only viable where electoral systems disadvantage smaller parties less, like the more democratic nations in the world.

There are qualifications to the rule. The FPP or SMD/P electoral system does allow for regional or local variation. Canada appears to present a multi-party system but actually consists of multiple provincial two party systems--the identity of the two parties just differs somewhat from province to province. The Liberals and Progressive Conservatives compete for parliamentary seats in Ontario while the Liberals and the Bloc Quebecois compete for parliamentary seats in Quebec. In Britain, the Welsh, Scottish, Unionist, and Irish nationalist parties consistently receive seats in Parliament despite receiving tiny percentages of the total vote because they have voting blocs concentrated in parts of their respective regions. For example, the Welsh National Party, Plaid Cymru, performs reasonably well in parliamentary constituencies in ethnically Welsh northern Wales. The survival of British Liberal-Democrat Party or Lib-Dems does not disprove the 'doomedness' thesis so much as demonstrates how difficult it can be for a third party to survive competition in an FPP or SMD/P electoral system. The Liberal Democrats have survived only by targeting a handful of seats in each general election where it has been able make a big impact locally.

Electoral reform in the U.S.

One possible solution that would allow for the emergence of viable third parties in the U.S. are electoral reforms such as adopting a Proportional Representation, Mixed Member, Single Transferable Vote electoral system for Congressional and state legislative elections.

Another possible cure for larger constituencies such as Presidential and state gubernatorial elections and Senate elections would be the adoption of a majority run-off electoral system such as "Range Choice" or "Instant Runoff" voting schemes.

And a third possibility would be to dramatically expand the current membership of the US House of Representatives thus creating smaller electoral districts in which money would play much less of a role in elections.